Few of the substances which we use for food are consumed in the state in
which they are originally produced by nature. With the exception of some
fruits and salads, all of them undergo some preparation. In most cases,
indeed, this is indispensable; for, otherwise, they would not only be
less wholesome and nutritive, but less digestible. The preceding
observations, therefore, are only applicable to the materials when
cooked, and not to the crude vegetables and raw flesh in the undressed
state.
The general processes of cookery resolve themselves into the various
modes of applying heat under different circumstances. They are the
following--roasting, frying, broiling, baking, stewing, and boiling.
These operations not only soften the raw materials, and render them
alimentary, but the chemical constitution of the cooked substance
suffers also such alterations, that its constituent parts can often no
longer be recognised.